The TRIP Database is a UK-based meta-search engine for clinical evidence. After typing in your search, you may apply filters from the right sidebar. TRIP does have a filter for PRIMARY RESEARCH and KEY PRIMARY RESEARCH AND CONTROL TRIALS.
Please note that this is an open-access (free) database, and the links to the articles will take you to PubMed records and not the actual articles themselves; therefore, if you identify any articles you would like to retrieve, you may need to record the citation information and search the NIC Library or check in Google Scholar @ NIC to see if we have access.
